Breast cancer: Hormone therapy overview

There are certain hormones that can attach to cancer cells and can affect their ability to multiply. The purpose of hormone therapy -- also called hormonal therapy or hormone treatment -- is to add, block or remove hormones.

With breast cancer, the female hormones oestrogen and progesterone can promote the growth of some breast cancer cells. So in these patients, hormone therapy is given to block the body's naturally occurring oestrogen and fight the cancer's growth.

There are two types of hormone therapy for breast cancer.

• Medicines that inhibit oestrogen and progesterone from promoting breast cancer cell growth.
• Medicines or surgery to turn off the production of hormones from the ovaries.

Do not confuse the term hormone therapy that is used for treating breast cancer patients with hormone replacement therapy that is typically used by post- menopausal women. Hormone therapy for cancer treatment stops hormones from getting to cancer cells. Hormone therapy for post-menopausal women without cancer (in the past called "hormone replacement therapy") adds more hormones to your body to counter the effects of menopause.

Who gets hormone therapy for cancer?

As part of the diagnosis process, tests are done to determine if the cancer cells have oestrogen or progesterone receptors. If so, that means that growth of the cancer can be stimulated with these hormones. If a cancer is found to have these receptors, hormone therapy is recommended as part of the treatment plan.

What medicines are used?

There are several common hormone therapy medicines used for breast cancer:

• Tamoxifen
• toremifene
• anastrozole
• exemestane
• letrozole
• goserelin

Tamoxifen

Tamoxifen is a pill that has been used for more than 20 years to treat breast cancer. Tamoxifen decreases the chance that some early-stage breast cancers will recur and can prevent the development of cancer in the unaffected breast. Tamoxifen also slows or stops the growth of cancer cells present in the body.

In addition, tamoxifen may offer an alternative to watchful waiting or prophylactic (preventative) mastectomy to women at high risk for developing breast cancer.

Tamoxifen is a type of medicine called a selective oestrogen-receptor modulator (SERM). At the breast, it functions as an anti-oestrogen. Oestrogen promotes the growth of breast cancer cells and tamoxifen blocks oestrogen from attaching to oestrogen receptors on these cells. By doing this, it is believed that the growth of the breast cancer cells are stopped.

Tamoxifen is often given along with chemotherapy and other breast cancer treatments. It is considered an option in the following cases:

1. Treatment of ductal carcinoma in situ (DCIS) along with breast-sparing surgery or mastectomy.
2. Adjuvant treatment of lobular carcinoma in situ (LCIS) to reduce the risk of developing more advanced breast cancer.
3. Adjuvant treatment of metastatic breast cancer in men and women whose cancers are oestrogen-receptor positive.
4. Treatment of recurrent breast cancer.
5. To prevent breast cancer in women at high risk for developing breast cancer.  However, some health experts do not recommend tamoxifen for use in prevention of breast cancer.